The invention pertains to a fiberscope or endoscope. Specifically, the invention relates to a fiberscope which may be used for observing a desired region ordinarily obscured by an opaque fluid. Such devices may be used, for instance, for optically observing and determining the condition of regions such as blood vessels and the heart which are ordinarily filled with blood, and also for industrial applications, for instance, in a tank filled with an opaque fluid.
A prior art fiberscope of the same general type to which the invention pertains is illustrated in FIGS. 1 through 3 of the drawings. The fiberscope includes a flexible tube 1 through which pass light guiding fibers 9 for transmitting illuminating light from a light source 3 to a region 5 to be observed, here, the interior of a blood vessel 7. An image transmitting fiber 11 also passes through the flexible tube 1. At the outer end of the image transmitting fiber 11 is providing a lens for forming an image of the object being observed. A fluid guide passage 15 is also provided within the flexible tube 1. The fluid guide passage 15 is used for introducing a clear fluid to the region between the lens at the end of the image transmitting fiber 11 and the object being observed. For instance, for medical uses, normal saline is an appropriate fluid. In the case illustrated in FIG. 1, normal saline is supplied from a syringe 13. A hood 17 is provided around the outward end of the flexible tube 1, light guiding fibers 9, image transmitting fiber 11 and fluid guide passage 15.
In use, the normal saline or other clear liquid is held within the hood 17 so as to provide a transparent region between the lens at the end of the image transmitting fiber 11 and the object to be observed. In the case that blood, for instance, is continuously flowing past the object to be observed, it is necessary to supply the normal saline at a flow rate approximately the same as the flow rate of the blood, typically, about 50 cm.sup.3 /sec.
As illustrated specifically by FIG. 3, in the prior art fiberscope, the liquid guide passage 15, which is cylindrical in cross section, is disposed between the inner walls of the tube 1 and the light guiding fibers 9. Due to physiologically imposed restrictions, the outer diameter of the tube 1 is limited to about 4 mm. Because of this fact, the effective cross-sectional area of the passage 15 was insufficient for introducing normal saline at a sufficient flow rate for normal blood flow rates.
As an alternative to the use of a clear solution, a transparent balloon can be blown up around the end of the fiberscope in the region to be observed. This approach, however, is not usable in many situations, particularly, in regions where it is not possible to interrupt the flow of blood because to do so would inflict injury to the patient.
It is thus a primary object of the present invention to eliminate the drawbacks of prior art fiberscopes described above.